1. FIELD OF THE INVENTION
The present invention relates to a roller assembly to be used, for example, as a conveyor roller. The invention also relates to a method for manufacturing a such roller assembly.
2. DESCRIPTION OF THE PRIOR ART
Usually, roller assemblies comprise a cylindrical tube which rotates on a shaft by means of bearings. U.S. Pat. No. 4,642,862 discloses a stone roller for a paper making machine provided with a shaft and two opposite ends. At each end, plates are provided and clamped with tie-rods extending all along the inner wall of the roller body. The tie-rods are fixed to the plates and sealed with a resin. The resin is used only as sealing and protective means.
The main problem arising with a conventional roller assembly is the damagement of bearings due to exterior contaminents and/or to vibrations.
Aforesaid bearings may be protected from exterior contaminents (such as dust particles) by sealing means such as labyrinth seals disclosed in U.S. Pat. No. 4,955,462. Also, U.S. Pat. No. 5,025,217, No. 5,261,528 and No. 3,944,055 disclose roller assemblies provided with bearings means and labyrinth seals. In these patents, the size of the roller body and the size of the other elements are very closely interdependent. Indeed, each of the element has to be precisely tooled to obtain a roller assembly of a predetermined size. Moreover, materials used in the manufacturing of these elements must have a sufficient compression resistance to allow a press fit assembling. Of course, this restricts the choice of materials which can be used for manufacturing rollers assemblies.
None of the roller assemblies of the prior art can be simultaneously long lasting, resistant to contaminents and/or vibration, and very easy and inexpensive to manufacture. Therefore, there is a very strong need for roller assemblies that can simultaneously have the aforesaid characteristics.